I took 20 seconds to Google "vegans protected UK" and find this article for you:
https://www.independent.co.uk/news/uk/home-news/vegans-discr...
https://www.independent.co.uk/news/uk/home-news/vegans-discr...
Just being protected and getting the wrong food at a restaurant doesn't necessarily follow that you've got legal recourse to do anything.
That wasn't part of your question.
Do you typically rely on others to read your mind, while asking questions?